/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.hadoop.fs.impl;

import javax.annotation.Nullable;

/**
 * Holds reference to an object to be attached to a stream or store to avoid
 * the reference being lost to GC.
 */
public class BackReference {
  private final Object reference;

  public BackReference(@Nullable Object reference) {
    this.reference = reference;
  }

  /**
   * is the reference null?
   * @return true if the ref. is null, else false.
   */
  public boolean isNull() {
    return reference == null;
  }

  @Override
  public String toString() {
    return "BackReference{" +
        "reference=" + reference +
        '}';
  }
}
